The Ultimate Guide to Professional Database Programming with Python and PostgreSQL

Book excerpt: Python has various database drivers for PostgreSQL. Currently, the psycopg is the most popular PostgreSQL database adapter for the Python language. The psycopg fully implements the Python DB-API 2.0 specification. The current version of the psycopg is 2 or psycopg2. The psycopg2 database adapter implemented in C as a libpq wrapper resulting in both fast and secure. The psycopg2 provides many useful features such as client-side and server-side cursors, asynchronous notification and communication, COPY command support, etc. PostgreSQL was designed to run on UNIX-like platforms. However, PostgreSQL was then also designed to be portable so that it could run on various platforms such as Mac OS X, Solaris, and Windows. PostgreSQL is free and open source software. Its source code is available under PostgreSQL license, a liberal open source license. You are free to use, modify and distribute PostgreSQL in any form. PostgreSQL requires very minimum maintained efforts because of its stability. Therefore, if you develop applications based on PostgreSQL, the total cost of ownership is low in comparison with other database management systems. In Chapter 2, you will learn querying data from the postgresql using Python including establishing a database connection, creating a statement object, executing the query, processing the resultset object, querying data using a statement that returns multiple rows, querying data using a statement that has parameters, inserting data into a table using Python, updating data in postgresql database using Python, calling postgresql stored function using Python, deleting data from a postgresql table using Python, and postgresql Python transaction. In Chapter 3, you will learn managing table structure and views including postgresql data types, postgresql create table, postgresql select into statement, postgresql create table as, using postgresql serial to create auto-increment column, identity column, alter table, drop table, truncate table, check constraint, not-null constraint, foreign key, primary key, unique constraint, managing postgresql views, creating updatable views, materialized views, creating updatable views using the with check option clause, and recursive view. In Chapter 4, you will learn statements, operators, and clauses including select, order by, select distinct, limit, fetch, in, between, postgresql like, is null, alias, joins, inner join, postgresql left join, self-join, full outer join, cross join, natural join, group by, having, intersect operator, except operator, grouping sets, cube, and rollup. In Chapter 5, you will learn postgresql trigger, aggregate, and string functions including creating the first trigger in postgresql, managing postgresql trigger, aggregate functions, avg function, max function, min function, sum function, postgresql concat function, ascii function, trim function, length function, substring function, regexp_matches function, regexp_replace function, replace function, to_number function, and to_char function.